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Aldehydes, Ketones and Carboxylic Acids · Question 45

AIPMT 2012 (Mains)MCQEasy📈 Topic in 38% papers+4−1
1

Consider the reaction : RCHO + NH2NH2 RCH = N - NH2 What sort of reaction is it?

  1. Electrophilic addition-elimination reaction
  2. Free radical addition-elimination reaction
  3. Electrophilic substitution-elimination reaction
  4. Nucleophilic addition-elimination reaction

Answer

(4) Nucleophilic addition-elimination reaction

Solution

The nitrogen of hydrazine (NH2NH2) has a lone pair and acts as a nucleophile.

Step 1 (nucleophilic addition): NH2NH2 attacks the electrophilic carbonyl carbon ⇒ RCH(OH)-NH-NH2

Step 2 (elimination): a molecule of water is lost ⇒ RCH = N - NH2 (hydrazone)

∴ As per NCERT, reactions of aldehydes and ketones with ammonia derivatives (Z-NH2) are nucleophilic addition-elimination reactions.

Answer: (4)

AIPMT 2012 (Mains)

Keep practising — Aldehydes, Ketones and Carboxylic Acids

2

Which of the following compounds will give a yellow precipitate with iodine and alkali?

  1. Acetophenone
  2. Methyl acetate
  3. Acetamide
  4. 2-Hydroxypropane
AIPMT 2012 (Mains)
3

Consider the following reaction [figure] The product A is

  1. C6H5CHO
  2. C6H5OH
  3. C6H5COCH3
  4. C6H5Cl
AIPMT 2012 (Mains)
4

In the following sequence of reactions CH3-Br KCNA H3O+B [ether]LiAlH4C the end product (C) is

  1. acetone
  2. methane
  3. acetaldehyde
  4. ethyl alcohol
AIPMT 2012 (Prelims)
5

CH3CHO and C6H5CH2CHO can be distinguished chemically by

  1. Benedict's test
  2. Iodoform test
  3. Tollens' reagent test
  4. Fehling's solution test
AIPMT 2012 (Prelims)
6

The correct order of decreasing acid strength of trichloroacetic acid (A), trifluoroacetic acid (B), acetic acid (C) and formic acid (D) is

  1. B > A > D > C
  2. B > D > C > A
  3. A > B > C > D
  4. A > C > B > D
AIPMT 2012 (Prelims)
7

Predict the products in the given reaction. [figure]

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2012 (Prelims)
8

Acetone is treated with excess of ethanol in the presence of hydrochloric acid. The product obtained is

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2012 (Prelims)
9

The order of reactivity of phenyl magnesium bromide (PhMgBr) with the following compounds: [figure]

  1. III > II > I
  2. II > I > III
  3. I > III > II
  4. I > II > III
AIPMT 2011 (Mains)
10

Clemmensen reduction of a ketone is carried out in the presence of which of the following?

  1. Glycol with KOH
  2. Zn-Hg with HCl
  3. LiAlH4
  4. H2 and Pt as catalyst
AIPMT 2011 (Prelims)
11

Following compounds are given (i) CH3CH2OH (ii) CH3COCH3 (iii) CH3- CH3 |CHOH (iv) CH3OH Which of the above compound(s), on being warmed with iodine solution and NaOH, will give iodoform?

  1. (i), (iii) and (iv)
  2. Only (ii)
  3. (i), (ii) and (iii)
  4. (i) and (ii)
AIPMT 2010 (Mains)

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